JPS61235750A - Flaw detector for weld zone - Google Patents

Abstract

PURPOSE:To reduce the size of a device and to improve its reliability by installing an infrared sensor means except at a prove follow-up mechanism and connecting a condenser lens provided to the probe follow-up mechanism to the infrared sensor by an optical fiber. CONSTITUTION:Two infrared-ray radiation type temperature sensors 30 are used and respective sensor heads 31 are connected by optical fibers 32. Infrared rays of extremely small areas P1 and P2 of a seam welded pipe 4 are converged by lenses of the heads 31 and transmitted to sensors 30 through the optical fibers 32. The infrared rays are intermitted by a mechanical chopper 33 to enter an infrared -ray detecting element 34 and specific signal processing is carried out by an electronic circuit 35 on the basis of the element 34, so that the quantity of displacement of a weld zone 3 is outputted to a servo-controller. Thus, the device is reduced in size and the reliability is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a welded part flaw detection device, and in particular, to detect the quality of a welded part of an ERW pipe online using an ultrasonic flaw detector immediately after pipe production. The present invention relates to a welding part flaw detection device used for inspection.

[Conventional technology]

In general, in automatic ultrasonic flaw detection of conduit welds, accurately positioning the ultrasonic probe relative to the weld, especially the most melted part during welding, improves the accuracy and reliability of flaw detection. It is necessary to do so.

In particular, on the pipe production line of an ERW pipe manufacturing factory, the quality of the welded part is inspected online using ultrasonic flaw detection immediately after pipe forming, welding, and bead removal. The twisting of the electric resistance welded pipe causes positional fluctuations in the pipe circumferential direction. It is necessary to accurately detect this changed position and control the ultrasonic probe.

By the way, various methods have been proposed as such means for detecting the position. For example, Japanese Patent Application Laid-open No. 157561/1989 discloses a method of detecting the welding position by using the temperature distribution near the welding part. has been done. This method focuses on the fact that the welded area immediately after pipe production has been formed and welded, so the area near the welded area shows a surface temperature distribution with the welded area being the highest temperature. The position of the highest temperature, that is, the position of the welded part, is detected by radiation measurement.

This conventional technology will be explained with reference to the drawings. In FIG. 2, 1 is a welding position detection device including an infrared detection means to be described later, 2 is an ultrasonic probe, 3 is a welding part, and 4
6 is an electric resistance welded pipe, and 6 is a signal processing unit that receives an output signal from the welding position detection device 1 and electrically processes the signal. The welding position detection device IH1 includes a lens X9, a mechanical chopper 10, and a two-quadrant infrared detector 11.

FIG. 3 is a diagram for explaining the conventional welding position detection method described above, and the song 1s12 shows the surface temperature distribution.

Point O is the welding position and has the highest temperature. Also, point A
, B are points located on opposite sides of point 0. The signals 13a and 13b are transmitted from the two-quadrant infrared detector 11.
The output signal is 14Fi, and the signal 14Fi is the difference signal.

Next, to explain the detection operation, the lens 9 and the two-quadrant infrared detector 11 are arranged so that two minute areas near the welding part 6 are imaged on the two infrared detection elements of the two-quadrant infrared detector 11, respectively. Placed. At this time, the two-quadrant infrared detector 11 is arranged so that the two infrared detecting elements are lined up in a direction perpendicular to the welding line direction, and the minute area on the ERW tube that each of the two infrared detecting elements sees is the welding line. Arrange them perpendicularly to the line direction.

The two-quadrant infrared detector 1 is operated by the mechanical chopper 10 disposed between the ERW tube 4 and the two-quadrant infrared detector 11.
When the infrared rays incident on the infrared rays 1 are interrupted, alternating current output signals 13 a and 13 b are output from the infrared detecting elements. The amplitudes of these output signals 13a and 13b are approximately proportional to the difference in the amount of infrared radiation between the minute area on the electric resistance welded tube 4 and the mechanical chopper 10.

As described above, the surface temperature 5 of the electric resistance welded tube 4 is much higher than the ambient temperature, and has a distribution like the curve 12. The maximum temperature position O may be considered to be on the welding part 3. Therefore, the electric resistance welded tube 4 imaged on the two-quadrant infrared detector 11
2 above depending on whether the center position of the micro region is as described above or in B.
The magnitude relationship between the output signals 13a and 13b of the two infrared detection elements is reversed. Using this relationship, the output signals 13a, 1
3b is taken, and from the phase of this difference signal 14, the position detecting device 1 determines the polarity to which side, A or B, the welding position has deviated from the maximum temperature position OK.

Furthermore, the amount of deviation from the maximum position O is determined from the amplitude of the difference signal 14.

Next, ultrasonic flaw detection for the welding position detected as described above will be explained with reference to FIG. 4. In FIG. 4, the probes 2a and 2 are placed between the welded part 6 of the
b are arranged facing each other. The probes are actually arranged for multiple channels.

These probes 2a and 2b irradiate the welded portion 3 with ultrasonic waves, and flaw detection is performed based on the presence or absence of reflected echoes of the ultrasonic waves. The probes 2 a and 2 b are held in a probe holder 16 so as to be symmetrical with respect to the welding part.
The bone is attached to b.

In this case, when the position of the welded portion 6 changes due to twisting of the electric resistance welded tube 4, the irradiation area of the ultrasonic waves 15a, 15b emitted from the probes 2a, 2b to the welded portion B changes. Therefore, it becomes impossible to perform flaw detection with high accuracy. Therefore, means is required to control the positions of the probes 2a and 2b to follow the welding position detected by the welding position detection device.

Next, an example of a welding part flaw detection apparatus having the above-mentioned probe tracking means will be described.

FIG. 5 shows a side view of such a flaw detection device, and FIG. 6 shows a front view. Further, FIG. 7 shows the main parts of the probe tracking means. 5 to 7, the probe holder 16 to which the contacts 2a, 2b, . . . are attached is connected to the probe head 1.
It is installed on 7.

This probe head 17 has a parallelogram link 18a.

18b, and the operation of the pneumatic cylinder 19 performs the osteotomy and the elevating and lowering of the female tube.

Fixed side member 20 of the parallelogram links 18a, 18b
has a member 21 having a substantially U-shaped cross section on its back surface, and a sector gear 24 is slidably held on this member 21. The sector gear 24 is fixed to a vertical member 23 which is fixed to the horizontal support beam 22. That is, the fixing member 20 is attached to the sector gear 2 with respect to the horizontal support beam 22.
The probe head 17 and the probe holder 1 are designed to rotate as the fixing member 20 rotates.
6 and the probes 2a, 2b are configured to rotate as a whole. On the other hand, a welding position detection device (1) is fixed to the probe head 17, and as the sector gear 24 rotates, the welding position detection device (1) also rotates.

Next, one side of the probe head 17Fi has an inverted V-shape, and this portion is in contact with the electric resistance welded tube 4 (see FIG. 6). Further, a servo motor 25 is attached to the side of the fixed member 20, and a pinion gear 26 is attached to the output shaft of the servo motor 25 so as to mesh with the sector gear 24, as shown in FIG. ing. A servo controller 27 is connected to the servo motor 25, and an output signal from the signal processing section 6 is input to the servo controller 27.

Further, a tacho generator 28 is connected to the servo controller 27 .

The displacement signal of the position B is input to the servo controller 27. The servo controller 27 drives the servo motor 25 based on the input displacement signal. This drive controls the positions of the probes 2a, 2b relative to the welding position 3.

[Problem that the invention seeks to solve]

By the way, in the conventional welding part flaw detection device as described above, two infrared detection elements are used as a two-quadrant infrared detector, and a mechanical chopper is interposed between the infrared detection means and the lens. Therefore, a commercially available infrared radiation thermometer cannot be used as is, and must be specially manufactured, which increases the cost and the external dimensions of the device. Therefore, when incorporating it into the probe holder tracking mechanism as described above,
The installation space becomes large.

Furthermore, since the welding position detection device is attached to the probe holder follow-up mechanism, there is also the disadvantage that it is subject to large vibrations or shocks during bone attachment in the follow-up operation and when the layer tube is raised and lowered.

The present invention has been made in view of the above problems, and an object thereof is to provide a highly reliable welded part flaw detection device that is small, easy to handle, and resistant to vibration and shock.

[Means for resolving Marei points]

In the present invention, the infrared sensor means is installed at a location other than the entire probe tracking mechanism, and the probe tracking mechanism is provided with a condensing lens for infrared rays, and this condensing lens and the infrared sensor means are connected with an optical fiber. It is characterized by the fact that

[For production]

Vibrations and shocks caused by the probe tracking mechanism are not transmitted to the infrared sensor means. Furthermore, the condenser lens and optical fiber are configured to be small and lightweight.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given of an embodiment of the welded part flaw detection apparatus according to the present invention, based on the accompanying drawings.

FIG. 1 shows a basic configuration example of the present invention.

In this figure, two sets of infrared radiation thermometer sensors (hereinafter simply referred to as "temperature sensors") 30 are prepared, each connected to a sensor head 31 by an optical fiber 32. A mechanical chopper 33 is included in the temperature sensor 30.
, an infrared detection element 34 , and an electronic circuit 35 such as an amplifier, and the infrared rays transmitted through the optical fiber 32 are interrupted by a mechanical chopper 63 and are made to enter the infrared detection element 34 .

On the other hand, the sensor head 31 has condensing lenses incorporated therein, and is fixedly attached to a mounting member 36 at appropriate intervals. These sensor heads 61 sandwich the welding line of the welding part 3 and detect a minute area P1. It is arranged so that the infrared rays emitted from P2 are incident.

A specific arrangement example is shown in FIG. 8, in which the sensor head 31 is attached to a bracket 37 extending on the inlet side of the probe head 17, that is, on the pneumatic cylinder 19 side. A temperature sensor 30 is fixed on the horizontal support beam 22.

Next, to explain the operation of the above embodiment, the area P1. shown in FIG. The infrared rays in the minute region P2 are each condensed by the condensing lens of the sensor head 31, introduced into the optical fiber 32 (see FIG. 9), and further transmitted to the Fi temperature sensor 60.

This infrared ray is interrupted by a mechanical chopper 63 and then enters an infrared detection element 64 . Then, predetermined signal processing is performed by an electronic circuit 65 based on the output of the infrared detection element 34.
The amount of displacement of the welding part B is output to the servo controller 27 (see FIG. 7).

That is, as shown in FIG. 9, the surface temperature near the welded portion immediately after welding has a symmetrical distribution with the welded portion 31r being the highest temperature. Therefore, the servo motor 25 is driven so that the outputs of the infrared detection elements 34 are equalized, and the sensor head 61 follows the position of the welding part 6. Due to this bacteriostatic control, the probes 2a, 2b, . . . also follow the positional changes of the welded portion 3.

On the other hand, since the temperature sensor 30 is provided on the horizontal support beam 22, it is not affected by vibrations or the like during the follow-up operation.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the temperature sensor 60 may be installed at an appropriate stable position that does not interfere with the tracking operation of the probe tracking mechanism, and may not necessarily be mounted on the horizontal support beam. You don't have to.

Furthermore, the target of flaw detection is not limited to the electric resistance welded pipe, but may also be a groove portion of other welded products.

〔Effect of the invention〕

As explained above, the welding part flaw detection apparatus according to the present invention has the following effects.

■ Only the sensor head, which consists of a condensing lens and an optical fiber terminal, is attached to the movable part, and the rest of the main body can be placed in a stable position by using optical fibers, so it is not affected by vibrations or shocks. difficult,
The occurrence of failures is reduced and reliability can be improved.

(2) Since the sensor head can be configured to be small and lightweight, it can be installed in a small space, and the overall device can be made smaller. Further, the work of aligning the optical axis and focusing on the object becomes easier.

■ It is inexpensive because a commercially available temperature sensor can be used.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the configuration of the main parts of the weld flaw detection device according to the present invention, FIG. 2 is a perspective view showing an example of a conventional welding position detection method, and FIG. 3 is the method shown in FIG. 2. 4 is an explanatory diagram illustrating the detection principle of the probe, FIG. 4 is an explanatory diagram illustrating the positioning of the probe, FIG. 5 is a side view showing an example of a conventional weld zone flaw detection device, and FIG. A front view, FIG. 7 is an explanatory diagram of the following mechanism, and FIG. 8 is a side view showing an embodiment of the present invention.
FIG. 9 is an explanatory diagram illustrating the following operation. 2a, 2b... Probe, 3... Welded part, 4... Electric resistance welded tube, 19... Pneumatic cylinder, 22... Horizontal support beam, 24... Sector gear, 60... ... Temperature sensor, 61 ... Sensor head, 62 ... Optical fiber, 3
4...Infrared detection element. Agent Patent Attorney Sanro Kimura No. 2 Flute No. 3 Prefectural Haru I? 1g! r leap figure 6 tIC9 figure

Claims (1)

[Scope of Claims] Welding part flaw detection in which the temperature distribution in the vicinity of the welding part is detected by an infrared sensor means, and the position of the probe is controlled by following the welding part by a probe tracking mechanism based on the detection result. In the apparatus, the infrared sensor means is installed at a location other than the probe following mechanism, and the probe following mechanism is provided with a condensing means for condensing infrared rays near the welding part, A welding part flaw detection apparatus, characterized in that the light condensing means and the infrared sensor means are connected by an optical fiber.